This research, which is an expanded version of a paper presented at the XVII SIMPOI - Symposium of Production Management, Logistics and International Operations, purported to discuss the concepts of mass customization in the automotive industry and how the use of lean principles in product development enables a profitable Design and Production customization. The results of a case study performed at an automaker plant in southern Rio de Janeiro state, Brazil, proved the efficiency of the company practice to develop simultaneously multiple concepts for each mechanism or Project detail, with substantial increase in design reliability, reducing redesign, cost, and development time, although cultural barriers were found.